Inhibitive and Adsorption Properties of Ethanol Extract of Seeds and Leaves of Azadirachta Indica on the Corrosion of Mild Steel in H2SO4

Abstract

The corrosion of mild steel in H 2 SO 4 was studied using gravimetric, gasometric and IR methods. The results indicate that the rate of corrosion of mild steel in H 2 SO 4 increases with increase in the concentration of the acid and that ethanol extracts of the seeds and leaves of Azadirachta indica inhibit the corrosion of mild steel in H 2 SO 4. Inhibition efficiencies of the leaves and seeds extract range from 82.62 to 94.24% and from 60.55 to 84.78%, respectively. The inhibition potential of these extracts is attributed to the presence of tannin, saponin, glycoside, anthraquinone, flavonone and other phytochemicals in the extracts. IR study confirms that the inhibitors are adsorption inhibitors and the adsorption of the inhibitors on mild steel surface is exothermic, spontaneous and consistent with the assumptions of Flory-Huggins adsorption isotherm. Based on the values of the activation, free energy of adsorption and the variation of inhibition efficiency with temperature, a physical adsorption mechanism is proposed for the adsorption of ethanol extract of leaves and seeds of Azadirachta indica on the surface of mild steel.

The Inhibition of Mild Steel Corrosion in an Acidic Medium by the Aqueous Extract of Leaves of Polyalthia Longifolia

“…The result obtained indicates that the adsorption of the extract is consistent with the mechanism of physical adsorption. For a physical adsorption mechanism, the activation energy should be less than 80 kJ/mol [7,[37][38][39][40]. Also, the values of E a obtained in the presence of the aqueous extract of P. longifolia leaves were higher than the value of 25.74 kJ/mol obtained for the blank, indicating that the extract inhibited the corrosion of mild steel in dil.…”

“…A number of biologically active compounds have been isolated from this plant [34][35][36]. The plant extract and isolated compounds were studied for various biological activities like antibacterial activity, cytotoxicity, antifungal activity [37][38][39][40].…”

"Corrosion Inhibition Efficiency of Human Black Hair Sample for Mild Steel in Phosphoric Acid "

“…The values are negative and lower than the threshold value of -40 KJ/mol which is indicative for chemisorption, and hence the inhibitor molecule get adsorbed on the mild steel surface is spontaneous and the mode of inhibition follows physical adsorption. [16][17][18] -5.0000 Potentiodynamic polarization measurements Potentiodynamic polarization curve and potentiodynamic polarization parameters of mild steel immersed in 1 M H3PO4 in the absence and presence of different inhibitor concentrations are given in Fig.-5 and Table-5. Important corrosion parameters like corrosion current, corrosion potential, Tafel slopes (ßa & ßc) were evaluated by potentiodynamic polarization measurements.…”

Corrosion Inhibition and Adsorption Behavior of Extract of <i>Funtumia elastica</i> on Mild Steel in Acidic Solution

“…It has been reported severally that most materials of plant origin which are used as corrosion inhibitors are rich in heteroatoms containing oxygen, nitrogen and/or sulphur in a conjugated system [16][17][18][19][20]. These materials function by adsorption of the material on the surface of the metal creating a barrier between the metal and the aggressive corrodent [21].…”